AT517186A1 - Gripper with at least one clamping element - Google Patents

Abstract

The invention relates to a gripper (1) having at least one first clamping element (2) and at least one second clamping element (3), wherein the at least one first clamping element (2) on a first side of a clamping gap (4) and the at least one second clamping element (2). 3) is arranged on a second, the first side opposite side of the clamping gap (4), wherein at least one of the clamping elements (2, 3) in segments (5, 6) is divided, at least in one to a longitudinal extent of the clamping gap (4 ) parallel to each other.

Description

The invention relates to a gripper with at least one first and at least one second clamping element, wherein the at least one first clamping element is arranged on a first side of a clamping gap and the at least one second clamping element on a second, the first side opposite side of the clamping gap.

Furthermore, the invention relates to a device for producing a workpiece from at least one sheet-like material, wherein the device has a shape corresponding to the workpiece for the film-shaped material.

In addition, the invention has a method for producing a workpiece from a film-shaped material to the object.

The term film or film-like in the present context, a flat structure understood that is flexible, at least in the longitudinal direction, preferably also in the transverse direction, in particular fabric and pre-impregnated fabric, prepreg, textile materials, etc.

Today, fiber composite materials are used in many industrial sectors. Especially in aviation and the automotive industry, such materials are being used more and more frequently due to their high lightweight potential. The high volume production of fiber composite components requires the development of new, automated processes to enable cost efficient production.

For the automated production of fiber composite components with carbon or glass semi-finished products processes are necessary that allow a defined storage of textile materials on a three-dimensionally shaped surface.

In the manufacture of rotor blades of wind turbines, it is known, for example, to apply belts to increase the buckling rigidity in the longitudinal direction along the rotor blade inner wall. These straps are usually made of constant width gussets in the laminating process. Such gussets may be, for example, laminates of GFRP films. In addition to the production of rotor blades can be used from these gussets belts as reinforcing or structuring elements in many other applications, such as in the automotive industry. However, when forming flat 2D semi-finished products into a doubly curved 3D shape, the material must be deformed to ensure high quality wrinkle-free deposition. In particular, it is necessary for this that the material can compensate for differences in length in the direction of deposition on the mold surface, in that individual fiber bundles can slip against each other (deformation by shearing). This is even more important the more complex the geometry is and the wider the strip of foil-like material that is deposited at one time.

From WO2010129492 A a device of the aforementioned type has become known, in which for applying / laying the film along an elongated shape with a concave cross section for producing a belt for a rotor blade at one end of the mold a plurality of storage rollers of the sheet-like material stationary in a Frame are arranged. From each of these rolls a film layer is peeled off and placed in the mold. After the layer has been built up, the individual film layers are connected to one another by lamination to form the belt. A disadvantage of the known state of the art is that, given a more complicated three-dimensional surface geometry of the mold, wrinkling and / or warping of the material may occur. This is due in particular to the fact that it is not possible in the known solution to stretch or stretch the film in sections to different extents. So far, no solutions have become known which make it possible to hold or pinch a film over an entire edge of the material and thereby stretch areas of the material differently.

It is therefore an object of the invention to overcome the abovementioned disadvantages of the prior art and to be able to deposit the deposit of film-like materials, in particular unidirectional semifinished fiber products, automatically on three-dimensional mold surfaces with high shape complexity.

This object is achieved with a gripper of the type mentioned according to the invention that at least one of the clamping elements is divided into segments which are separated from each other at least in a direction parallel to a longitudinal extent of the nip direction.

The segmented gripper makes it possible to compensate for the differences in length occurring within the web during the storage of the film-shaped material. This can be done by partial slipping out of individual sections or fibers or fiber bundles of the material from the clamp. The clamping force can be adjusted so that the web does not slip by its own weight from the clamp. However, if a section is stretched when pressed against a mold, it can move until the equilibrium of forces is restored. In this case, the adjacent section or fiber bundle remains in position, as act on this or this no or less tensile forces. Thereby, the change in length can be compensated for when draping the film-shaped material within the web.

In order to ensure a precisely defined extensibility of the film-shaped material over the entire length of the clamping gap, it can be provided that the segments have the same length parallel to the longitudinal extent of the clamping gap.

According to an advantageous variant of the invention, it can be provided that both the at least one first clamping element and the at least one second clamping element are subdivided into segments which are separated from each other at least in a direction parallel to a longitudinal extent of the clamping gap.

It is particularly advantageous if each segment of the at least one first clamping element faces a segment of the at least one second clamping element, wherein a segment of the at least one first clamping element and a segment of the at least one second clamping element opposite this segment form a pair of gripping jaws.

According to a preferred variant of the invention, it may be provided that the segments forming a pair of gripping jaws are displaceably mounted in a direction normal or transverse to the longitudinal extension of the clamping gap. Since the gripping jaws can follow the movement of a portion of the film during clamping, in this variant of the invention can be prevented that the film slips between the clamping elements and it comes to a contamination of the gripper, for example with a resin of the film.

Furthermore, the gripper may have a knife. In this way, an edge of the film, which is clamped between the clamping elements, easily crop, so that a later trimming this edge is not necessary.

In a further embodiment can be dispensed with the knife when the blank of the sheet-shaped material, the different change in length of different sections of the material is kept. Here, the tool geometry determines the segmental length of the film-shaped material to be applied using an algorithm, in particular a CAD-CAM program, and the blank is selected such that the edge formed by the shear of the material forms the edge of the component. The resulting component edge accuracy depends on the segmentation of the gripper. The advantage of this method is the elimination of waste and the saving of material as well as the process time gained, since the blank takes place parallel to the main time.

The above object can also be achieved with a device of the type mentioned in the present invention in that it has at least one gripper according to one of claims 1 to 6.

Picking up the prefabricated film and transporting the recorded film to the mold and depositing the film on the mold by means of the gripper can be accomplished by the at least one gripper being mounted so as to be linearly movable at least in two mutually orthogonal directions.

An optimum laying of the film or of the material on the mold adapted to the contour of the mold can be achieved by the at least one gripper being mounted so as to be rotatable about at least one axis.

In order to ensure optimum tensioning of the film or of the material during placement on the mold, it can be provided that the device has at least two grippers and at least two opposing portals, wherein each of the grippers can be linearly displaced along one of the at least two portals is. Each of the at least two grippers is in this case preferably designed according to claims 1 to 6.

According to a favorable embodiment of the invention, which is characterized by a simple structure, it can be provided that between the two portals, a longitudinal beam of the two portals connecting cross member is arranged, wherein the cross member is slidably mounted in a longitudinal extent of the longitudinal members of these, wherein the at least two grippers are displaceably mounted along the cross member and transversely to the longitudinal extension of the side members.

In order to ensure optimal tensioning of the film, it can be provided that the grippers are each mounted vertically displaceable in displaceable along the cross member guides.

In order to be able to compensate for the deviation which arises transversely to the longitudinal extent in tool geometries of different degrees of curvature, it is advantageous for the grippers to be displaceable transversely to the longitudinal extent. This is necessary insebonde- re when the grippers are arranged on a common cross member. The deviation is due to the different projection length of the same arc lengths on differently curved surfaces. Over several parallel deposited strips of material add up these deviations.

In order to achieve an optimal depositing result with very different curvatures transversely to the longitudinal extent, it is advantageous if the films or the material are also prefabricated along the longitudinal edge. Especially when the longitudinal edge coincides as a component edge. By now possibly no longer continuous film sections and / or fiber bundles an adaptation of the clamping forces for the non-continuous film section is provided.

Furthermore, it may be provided that the grippers are rotatably mounted on the guides in each case about at least one, preferably parallel to the cross member, extending axis.

As an alternative to the use of portals, the at least one gripper can also be arranged on at least one robot arm.

In order to adapt the material to be deposited to the mold, the apparatus may comprise at least one cooperating with the mold pressure head for the film-shaped material.

To be particularly favorable, it has been found that the at least one pressing head has at least one pressure roller.

In order to enable different directions of the film-shaped material in the mold in a simple manner, it can be provided that the mold is rotatably mounted about at least one axis.

A prefabricated material can be achieved simply by the device having a holder for a storage roll of the material and at least one cutting device for cutting the material.

The abovementioned object can also be achieved with a method of the type mentioned at the outset by trimming a sheet of the film-shaped material in a step i) and this web in a step ii) by means of two grippers which are according to claims 1 to 6 are trained, picked up and positioned over a mold, wherein in a step iii) the web is pressed by means of a pressing head against the mold and adjusted by moving the contact pressure of the contour of the mold, during step iii) the web is tensioned by means of the gripper , At the same time, it is possible in step iii) to control the deposit from the longitudinal edge of the web to the already deposited longitudinal edge of the previously deposited web defined by movements of the grippers. Thus, overlapping of deposited webs can be prevented or a defined maximum gap size can not be exceeded. In particular, the method according to the invention can be carried out with a device according to one of claims 7 to 18.

In order to ensure the possibility of different longitudinal displacements of strips of the material web, it may be provided that parallel cuts are made in the web before step ii), the distance between two cuts preferably being smaller than the length of a segment of the at least one segmented clamping member, each of the grippers, or equal to the length of a segment of the at least one segmented clamping member, is each of the grippers. In order to keep the position of the sections to each other, it is advantageous if the cuts are discontinued. The longitudinal cuts thus reduce the shear strength between two sections and can not be performed consistently in depth.

For a better understanding of the invention, this will be explained in more detail with reference to the following figures.

In each case, in a highly simplified, schematic representation:

Fig. 1 is a perspective view of a first variant of a gripper according to the invention;

2 shows a perspective view of a second variant of a gripper according to the invention;

Fig. 3 is a perspective view of a device according to the invention.

By way of introduction, it should be noted that in the differently described embodiments identical or similar parts are provided with the same reference numerals or identical component names, wherein the disclosures contained in the entire description can be mutatis mutandis to the same parts with the same reference numerals or component names. Also, the location information chosen in the description, such as top, bottom, side, etc. related to the immediately described and illustrated figure and these position information in a change in position mutatis mutandis to transfer to the new location.

According to FIG. 1, a gripper 1 according to the invention has a first clamping element 2 and a second clamping element 3. The first clamping element 2 is arranged on a first side of a clamping gap 4 and the second clamping element 3 on one of the opposite side of the clamping gap 4. In the illustrated embodiment, the clamping element 2 is divided into segments 5, which are separated from one another at least in a direction parallel to a longitudinal extension of the clamping gap 4. The second clamping element 3 is formed in the illustrated embodiment as a roller. The individual segment 5 can all be subjected to the same force or with different forces; this can be done, for example, by means of corresponding actuators, for example hydraulic, pneumatic, hydropneumatic cylinders or mechanical or electromechanical actuators. Also, the individual segments 5 can all be jointly or individually loaded with a spring which presses the segments 5 against the second clamping element 3.

As a result of the separation of the segments 5, it is possible that with locally different tensile forces acting on a material held in the gripper 1, individual sections of the material, which in each case correspond to a segment 5 in their width, move against each other and thus into one and the same material al different longitudinal expansions or longitudinal displacements of the material to realize.

The gripper 1 or the clamping gap 4 can be opened by means of one or more actuators, which or which for this purpose move the first clamping element 2 and / or the second clamping element 3.

As can also be seen from FIG. 1, the segments 5 can have the same length parallel to the longitudinal extent of the clamping gap.

According to FIG. 2, both the first clamping element 2 and the second clamping element 3 can be subdivided into segments 5, 6, which are separated from each other at least in a direction parallel to a longitudinal extension of the clamping gap 4. Each segment 5 of the first clamping element 2 can in this case a segment 6 of the second clamping element 3 are opposite. A segment 5 of the first clamping element 2 and a segment 6 of the second clamping element 3 each form a pair of gripping jaws between which a film-like material, in particular of a fiber composite material, can be clamped. The segments 5, 6 forming a pair of gripping jaws can be displaceably mounted normal or transversely to the longitudinal extension of the clamping gap 4. In this way, in the case of a tensile force acting on the portion of the material clamped therein, the gripping jaws can move in the direction of this pulling force. This prevents soiling, which could occur if the segments 5, 6 were arranged immovably in the direction of the tensile force in the gripper 1. Such soils may be due to a portion of the clamped material being pulled out of a pair of segments 5, 6 and a matrix material of the material, such as resin, being scraped off.

Due to the linear mobility of the segments 5, 6 transversely to the nip 4, the gripper 2 shown in FIG. 2, in contrast to the (passive) gripper shown in FIG. 1, can actively generate a tensile force by displacing at least one pair of gripping jaws and thus lying next to one another Move fiber bundles of material against each other in a longitudinal direction. The individual pairs of jaws, which are formed by the segments 5, 6, for this purpose can be controlled individually or moved individually by means of actuators.

In addition, the gripper 1 may have a knife to cut an edge of a clamped material can.

Referring to Fig. 3, an apparatus 8 according to the invention for producing a workpiece from a sheet-like material, for example a prepreg or other textile material provided with a resin, has a mold 9 corresponding to the workpiece into which the material is placed. Furthermore, the device 8 has two grippers 1, both of which can be designed as described above and in FIG. 1 or FIG.

The grippers 1 can be mounted to be linearly movable at least in two mutually orthogonal directions and to be rotatable about at least one axis. The directions of movement of the gripper 1 are indicated in Fig. 3 with arrows.

The grippers 1 can be arranged linearly displaceable, for example, on two opposing portals 10 of the device 8. Between the two portals 10, a two longitudinal beams 11 of the portals connecting cross member 12 may be arranged. The cross member 12 may be guided in a longitudinal extension of the longitudinal member 11 to this slidably. The grippers 1, in turn, can be displaceably mounted along the cross member 12 and transversely to the longitudinal extent of the longitudinal members 11. In addition, the gripper 1 can be vertically displaced in each case along the cross member 12 slidable guides 13. Also, the gripper 1 can be rotatably mounted on the guides 13 in each case by at least one, preferably parallel to the cross member 12 extending axis. It should be noted at this point that instead of the embodiments shown in FIG. 3 with portals 10, embodiments without these portals are also possible, wherein the grippers 1 can be arranged, for example, on at least one robot arm.

The device 8 has a cooperating with the mold 9 pressing head 14 for the material. The pressing head 14 may, for example, a roll Anpress 15 have. The mold 9 can be rotatably mounted about a (vertical) axis. Furthermore, the device 8 may comprise a holder 16 for a storage roll 17 of the material and at least one cutting device for cutting the material. The holder 16 is indicated in Fig. 3 by a transverse through the storage roller 17 extending axis of rotation.

According to the method according to the invention for producing a workpiece 19, in a step i) a web 18 of the material is cut to size. For example, the material may be withdrawn from the storage roll 17 and trimmed by means of the cutting device mentioned in the last paragraph. The web 18 is detected in a step ii) by means of the gripper 1, and positioned over the mold 9. In a step iii), the web 18 is pressed by means of a pressing head 14 against the mold 9 and adjusted by moving the contact pressure of the contour of the mold, in this case the web 18 is tensioned by means of the gripper 1. The laying of the web 18 may be computer controlled and monitored with a camera, for example, for crevices or wrinkles, and the grippers 1 controlled accordingly to prevent errors in matching the web 18 to the mold 9. In this case, an automatic compensation of the differences in length in the web by the gripper to avoid wrinkles in the tray takes place. After the web 18 has been deposited, the grippers 1 can return to a pickup position and pick up a new web 18. The necessary for the storage of semi-finished fiber on a non-developable geometry steps and components are spatially and temporally separated from each other.

For the production of the workpiece 19, a plurality of layers of the webs 18 can be stored one above the other, wherein an orientation of the webs 18 to each other can change. Thus, the webs 18, for example, also be placed obliquely or transversely to each other. The webs 18 are preferably fiber composite mats, in particular unidirectional fiber composite mats - ie mats with substantially parallel fibers embedded in a matrix, for example of resin, adhesive or a thermoplastic material.

It should also be mentioned at this point that it is advantageous if pressing of the web 18 onto the mold 9 begins in a middle region of the mold 9 or the highest point of the mold 9, since in this way a higher level of accuracy can be achieved ,

The mold 9 can be rotated before depositing the web into a desired position or aligned with respect to the web 18. In addition, the mold 9 and / or the pressing head 14 may be heated in order to facilitate a connection (laminating) of individual superimposed layers of webs 18 together.

In order to ensure a good longitudinal displacement of fiber bundles of the web 18, which are clamped by different adjacent segments 5, 6 of the gripper 1, prior to step ii) in the web 18 parallel cuts are introduced. The distance between two sections may correspond to the length of a segment 5, 6 or else be smaller or larger. Unidirectional semi-finished fiber products, as they can be used for the web 18, are usually stabilized by adhesive threads or sewing threads, so that the material is easy to handle. However, these threads hinder the mobility of the individual rovings of the web to each other. Therefore, it makes sense to cut these warp threads in areas with high degree of deformation before. In the case of the system according to the invention, this can be done, for example, by means of a CNC cutter, which cuts through the fixing threads longitudinally to the fiber without significantly damaging the fiber structure. In addition, the cutter can divide the semi-finished product into the currently required track length. In this way, commercial semi-finished products can be easily tailored to the current requirements. Furthermore, the material can compensate for differences in length in a direction of deposition on the surface of the mold by allowing individual fiber bundles to slide against each other (deformation by shearing).

List of Reference Numerals 1 Gripper 2 Clamping element 3 Clamping element 4 Clamping gap 5 Segment 6 Segment 7 Actuator 8 Device 9 Form 10 Portal 11 Longitudinal member 12 Cross member 13 Guide 14 Pressing head 15 Pressing roller 16 Holder 17 Storage roller 18 Path 19 Workpiece

Claims (21)

claims 1. Gripper (1) with at least one first clamping element (2) and at least one second clamping element (3), wherein the at least one first clamping element (2) on a first side of a clamping gap (4) and the at least one second clamping element (3) is arranged on a second, the first side opposite side of the clamping gap (4), characterized in that at least one of the clamping elements (2, 3) is divided into segments (5, 6), at least in one to a longitudinal extent of the clamping gap ( 4) are separated from each other in the parallel direction. 2. Gripper according to claim 1, characterized in that the segments (5) parallel to the longitudinal extension of the clamping gap have the same length. 3. Gripper according to claim 1 or 2, characterized in that both the at least one first clamping element (2) and the at least one second clamping element (3) are divided into segments (5, 6), at least in one to a longitudinal extent of Clamping gap (4) parallel direction are separated. 4. Gripper according to claim 3, characterized in that each segment (5) of the at least one first clamping element (2) a segment (6) of the at least one second clamping element (3) is opposite, wherein a segment (5) of the at least one first clamping element (2) and a segment (6) of the at least one second clamping element (3) opposite this segment (5) forming a pair of gripping jaws. 5. Gripper according to claim 4, characterized in that the pair of gripping jaws forming segments (5, 6) are displaceably mounted in a direction normal or transverse to the longitudinal extent of the clamping gap (4) extending direction. 6. Gripper according to one of claims 1 to 5, characterized in that the gripper (1) has a knife. 7. Device (8) for producing a workpiece from at least one sheet-like material, wherein the device (8) has a shape corresponding to the workpiece (9) for the sheet-like material, characterized in that it comprises at least one gripper (1) according to one of Claims 1 to 6. 8. The device according to claim 7, characterized in that the at least one gripper (1) is mounted linearly movable at least in two mutually orthogonal directions. 9. Apparatus according to claim 7 or 8, characterized in that the at least one gripper (1) is rotatably mounted at least one at least about an axis. 10. Device according to one of claims 7 to 9, characterized in that the device (8) has at least two grippers (1) and at least two opposing portals (10), wherein each of the gripper (1) along one of the at least two portals (10) is linearly displaceable. 11. The device according to claim 10, characterized in that between the two portals (10) a longitudinal member (11) of the two portals connecting cross member (12) is arranged, wherein the cross member (12) in a longitudinal extent of the longitudinal members (11) to this is slidably mounted, wherein the at least two grippers (1) along the cross member (12) and transversely to the longitudinal extent of the longitudinal members (11) are displaceably mounted. 12. The apparatus according to claim 11, characterized in that the grippers (1) in each case along the cross member (12) slidable guides (13) are mounted vertically displaceable. 13. The apparatus according to claim 12, characterized in that the grippers (1) are rotatably mounted on the guides (13) each at least one, preferably parallel to the cross member (12) extending axis. 14. Device according to one of claims 6 to 9, characterized in that the at least one gripper (1) is arranged on at least one robot arm. 15. Device according to one of claims 7 to 14, characterized in that it comprises at least one with the mold (9) cooperating pressing head (14) for the film-shaped material. 16. The apparatus according to claim 15, characterized in that the at least one pressing head (14) has at least one pressure roller (15). 17. Device according to one of claims 7 to 16, characterized in that the mold (9) is rotatably mounted about at least one axis. 18. Device according to one of claims 7 to 17, characterized in that it comprises a holder (16) for a storage roller (17) of the film-shaped material and at least one cutting device for cutting the film-shaped material. 19. A method for producing a workpiece (19) from a film-shaped material, characterized in that in a step i) a web (18) of the film-shaped material is cut to size and this web (18) in a step ii) by means of two grippers (1 ), which are formed according to claims 1 to 6, and is positioned over a mold (9), wherein in a step iii) the web (18) by means of a pressing head (14) pressed against the mold (9) and by moving the pressing head is adapted to the contour of the mold, wherein during step iii) the web is tensioned by means of the grippers (1). 20. The method according to claim 19, characterized in that prior to step ii) in the web parallel cuts are introduced. 21. The method according to claim 19 or 20, characterized in that the web (18) during step iii) defined by movements of the gripper (1) in particular transversely to the longitudinal extent to a pre-laid web is stored.